Flower-like Co3O4 sensor with rich oxygen vacancy defects for enhancing room temperature NOx sensing performances

Abstract

Flower-like Co3O4 microspheres (Co3O4-f) composed of thin nanosheets with a thickness about 5 nm were successfully synthesized with a simple solvothermal method and a subsequent calcination method. The sample microstructures and morphologies were characterized by XRD, FT-IR, TEM and EPR. The gas sensitivity test results showed that Co3O4-f exhibited a higher response (72.3%) to 100 ppm NOx and a lower detection limit (less than 70 ppb), which was about twice that of Co3O4 nanoparticles (Co3O4-p). Such outstanding gas sensing performance inherent in Co3O4-f may be attributed to its flower-like structure assembled from thin nanosheets, a large amount of chemisorption oxygen, and oxygen vacancies on the Co3O4-f surface. The mechanism for enhanced gas response and its wide range of applications are discussed in detail in this paper.